When creating variables, the variable name must always start with a letter and cannot contain spaces, though numbers and underscores are allowed to be contained in it also.

Create a function which returns true if a given variable name is valid, otherwise return false.

Examples

variable_valid("result") ➞ true

variable_valid("odd_nums") ➞ true

variable_valid("2TimesN") ➞ false

Notes

• Inputs are given as strings.
• Variable names with spaces are not allowed.
• Although this question may seem like otherwise, you can't actually assign words with quotes around them as variables.